Welcome to the Platonic Realms Interactive Mathematics Encyclopedia, a growing collection of articles on core topics written expressly for math students and enthusiasts at all academic levels. To begin, simply browse through the topics using the listings directory on the left side of the page. Click on a letter to browse alphabetically, and hover over any listing to see a brief definition or description. If the description ends with an ellipsis (…) then the article you get to by clicking on the listing will be longer and more detailed.

Each article on PRIME was written by one or more professional mathematics educators and each is independently reviewed for mathematical and pedagogical soundness. Also, unlike other math encyclopedias, the level and tone of each article is adjusted to the academic level at which a student would ordinarily be encountering the topic for the first time.

The collection of articles on PRIME is constantly growing. If you would like to be notified when new articles are published, please let us know using the contact page. (Please also let us know about any errors you find or suggestions you might have. We love to hear from our readers.) If you are a mathematics educator and you are interested in being a contributor to PRIME, please click here.